1. Field of the Invention
The present invention relates to an arrangement in the form of a fixture for effective anchoring even in a jaw bone with a combination of soft and hard bone portions (or inlays/grafts), which fixture can be applied in a hole having a diameter smaller than the diameter of the fixture in order to produce a clamping effect on the implant from the soft bone portion or portions.
2. Description of the Related Art
It is already known to adapt implants individually to soft and hard bones. Various implants and methods have been proposed to meet the different requirements which arise in hard jaw bone and soft jaw bone situations, and two different implant types and implant characters have in principle been used for the two different bone types.
For example, in a fixture or implant exclusively for soft jaw bone, it is possible to use a slightly conical implant in accordance with Swedish patent 516 917 obtained by the same Applicant as is filing the present application. The implant is in this case provided with thread turns which permit excellent integration with the bone substance and prevent breaking-off of fine bone trabeculae when the fixture is being screwed into the bone.
However, there are clinical situations in which soft jaw bone may be present in combination with hard jaw bone portions or grafts with different degrees of hardness, which are located like islands amid the softer jaw bone. The present-day fixtures for soft bone which are applied in holes with a smaller diameter than the fixtures concerned have a limited ability to expand and penetrate the hard bone portions or equivalent in question, and instead have the result that the fixtures press the hard bone portions aside. In addition, the hard bone portions may interfere with the threading of the bone. All of this can result in unsatisfactory or defective fixture installations.